My 5 month baby has a cold and breathing harder, and I see his ribs move. Should I take him to the e.R.?

In brief:
Yes

This is the use of extra muscles to breath. It is a subtle sign of respiratory problems such as wheezing or pneumonia. I would first call your pediatrician and try to be seen by him/her.

In brief:
Yes

What you are describing are called retractions.

This is the use of extra muscles to breath. It is a subtle sign of respiratory problems such as wheezing or pneumonia. I would first call your pediatrician and try to be seen by him/her.
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